Method and apparatus for controlling the gray scale response of a multilayer image forming screen
US4158564A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 3, 1978 |
| Grant date | Jun 19, 1979 |
| Priority date | — |
| Expiry date | Jan 3, 1998 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03G15/051
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
An electrostatic latent image is impressed on a multilayer apertured screen to establish within the apertures electric fields that modulate the passage of charged particles through the screens so that the charged particles are distributed in correspondence with the image. After imaging the screen is operated to control the gray scale response thereof in order to optimize copy quality. The gray scale screen response is expanded by applying a bias voltage of at least two different values to the screen during the duplication interval. The response is limited by altering the latent image charge to provide a high density cutoff and by applying a bias voltage to establish a low density cutoff during the duplication interval. Copy quality is further improved by adjusting the integrated charged particle current to establish the desired degree of density in regions of the copy image corresponding to high density regions of the original image.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.